M8×40 Carbon Steel Grade 8.8 Black Cylinder Head Flange Bolts

The M8×40 specification suits a wide range of light engine covers, manifold flanges, accessory brackets, and automotive structural connections. Grade 8.8 carbon steel provides excellent strength-to-cost performance, with a minimum tensile strength of 800 MPa and heat resistance appropriate for standard automotive operating temperatures. The black oxide surface treatment reduces glare and offers basic protection suitable for lubricated or enclosed assemblies.
Cylinder head bolts from our range comply with OEM specifications and are suitable for engines in passenger vehicles, light commercial vehicles, generator sets, and power equipment. Where higher strength is required (e.g., turbocharged or heavy-duty diesel engines), 10.9 and 12.9 alloy steel grades are available, along with SCM435 and 42CrMo material options. Surface choices include Zinc and Phosphate. Full OEM/ODM customization supported.